The present invention is generally directed to a core for holding web material and in particular to a core for holding film within a film cartridge.
Cores for holding web material are well known in the art. Such devices find considerable application in film cartridges for microfilm readers. Microfilm readers generally includes an integral container providing its own film aperture plate and in which a spool of microfilm can be stored or used merely by snapping the cartridge over the spindles of the reader transport apparatus. By keeping the film in the cartridge, the two hubs of the cartridge may be spaced apart less than twice the radial dimension of the accumulated film. Thus, there is completely eliminated any necessity for the operator to thread the film after reference has been made to any specific micro image on the film. Additionally, the integral cartridge container offers positive protection of the film. In actual use, cartridges hold as much as 215 feet of 0.003 film which never leaves the cartridge.
Such cartridges utilize film cores for holding the web film material and which rotate so that the film is wound about the cores. During the operation of such devices, it is occasionally necessary to completely rewind the film which places a relatively high pulling force on the film when the film is completely rewound. Thus, it is one requirement of the film cores to securely hold the film so that the end of the film does not break loose from the film cores during such operation.
While film cores in the past have been generally successful, they have been relatively complicated ad expensive to produce because they usually require a plurality of individual parts. Thus, in fabricating such cores, it is necessary to fabricate more than one part and then assemble the parts with the film in order to provide a complete cartridge.
It is therefore a general object of the present invention to provide a new and improved core for holding web material.
It is a more specific object of the present invention tp provide a new and improved core for holding microfilm within a microfilm cartridge.
It is a still more particular object of the present invention to provide a core for holding web film material which securely holds the film and which includes only a single part rendering the improved core less expensive to manufacture.